The Sky This Month

March 2010

Overview

March is a “change over” month for the night sky. The bright stars of the northern winter move westward and give way to the star-sparse nights of March, April, and May. That’s because we’re starting to look out of the plane of the Milky Way and into intergalactic space. So we see fewer stars and nebulae and open star clusters, but more galaxies become visible, especially those of the Virgo cluster and smaller collections like the M81 and Leo groups.

And of course, the seasons change this month. The southern hemisphere begins fall and the northern hemisphere begins spring on March 20 at 17:32 UT. At this time, the sun sits at the point where the celestial equator and ecliptic meet. All points on the Earth receive an equal amount of sunlight, hence the term “equinox”, or “equal nights”.

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For deep sky sights, try the two Messier objects in Cancer, M44 and M67. Both are old open clusters. The better-known M44 is more spread out and brighter, but M67 is fun to examine because its shape conjures many analogies. Some say M67 looks like a fountain of stars. Others suggest a “Pac-man” shape. What can you see?

Open clusters M44 (the “Praesepe”), center-right, and M67, lower right. Also, the spiral galaxy NGC 2903 (center)

And if you’re keen to see a nice galaxy, check out NGC 2903, just off the nose of Leo. This lovely 9th magnitude spiral is one of the best in this part of the sky. It was just missed by Messier; William Herschel discovered this galaxy in 1784. It lies 21 million light years away. Here’s what it looks like in a big telescope…

As for planets, Mars lingers in western Cancer, not far from M44 and M67. It’s fading this month, but a good telescope, high magnification, and steady sky will reveal a few surface features.

And Saturn is set to take center stage for planet lovers. The planet reaches opposition on March 21 and will reach its brightest over the next few months. More on Saturn below…

Moon

Last Quarter: March 7, 15:42 UT
New Moon: March 15, 22:01 UT
First Quarter: March 23, 11:00 UT
Full Moon: March 30, 2:25 UT

Planets

Mercury lies a generous 10 degrees above the western horizon after just after sunset. It reaches magnitude -0.9 by month’s end and sits just below the brighter Venus.

Venus is still close to the sun in the western sky, but it rises higher this month to get 10-12 degrees above the horizon by March 31. It’s not much to see through a telescope since it’s near full phase. But it makes a lovely pairing with Mercury later this month, and with the Moon on March 16-17.

Mars lingers in the sky, as mentioned above. At its closest in January, the disk of Mars was 14 arc-seconds across. It will shrink to 9 arc-seconds by month’s end.

Jupiter is lost in the glare of the sun this month.

Saturn gears up for a good show over the spring and early summer. The ringed planet hovers in Virgo between the stars Spica and Denebola. The planet is directly opposite the sun on March 21, and rises high enough for viewing by mid-evening. The rings are still just 4 degrees from edge-on. A small telescope at 75x or more will clearly show the rings. Saturn this month is about 1.27 billion km away from Earth.

Saturn lies in Virgo, between Spica and Denebola.

Uranus is too close to the sun to be observed this month.

Neptune. Just above the horizon at dawn. Wait for a month or two to try to spot this icy giant planet.

Celestial Events

The March equinox occurs at 17:32 UT, bringing spring and autumn to the northern and southern hemispheres.

And don’t forget to check out the zodiacal light early this month. Look for a tall pyramid of whitish-yellow light just after sunset. Dark sky is required.